Ziadoon Mohammed Rahi Al-hadrayi

Main problem is naturally raised is how to improve the efficiency and uses of composite materials in the aircraft structures and the aerospace industries. This paper deals with the studying of the effect of stacking sequences for the composite laminate on the failure modes under low velocity impact. Using the carbon fiber reinforced polymer (CFRP) in different layups as three groups (A, B, C). It has same material system but with different stacking sequences to investigate the effect that on failure modes and the composite material resistant to the impact. As well as understanding of the deformation mechanism and the damage that occurs in the laminates under low velocity impact. Through the results of experimental methods were the effect of stacking sequence on failure modes is very clear. Keywords - stacking sequences, delamination area, depth of indentation, composite laminates.

The nonlinear vibration behavior of rotating functionally graded carbon nanotube-reinforced composite (FG-CNTRC) beams is investigated with the impact of carbon nanotube (CNT) distribution patterns and system parameters. Five CNT distribution patterns are considered: Uniform Distribution (UD), Functionally Graded Λ-shaped (FG-Λ), V-shaped (FG-V), Outer (FG-O), and X-shaped (FG-X) to analyze their influence on the mechanical and dynamic properties of the beams. Utilizing Galerkin's method, the frequency ratios are determined with varying amplitudes, hub rotational radii, and volume fractions of CNTs. Statistical results reveal that the FG-Λ distribution gives the highest frequency ratio, enhancing by around 18-20% as compared to the UD configuration, while the FG-O and FG-X distributions represent intermediate improvements. The finding illustrates that a modification in the CNT volume fraction from 0.12 to 0.28 results in a significant increase in the system stiffness with increasing frequency ratios ranging from 1.36 to 2.0 at the peak amplitudes. Additionally, the effect of a hub radius (r = 0.5) also increases the frequency ratio by 6-8%, hence demonstrating the material and geometric parameters' synergy. These findings emphasize the importance of optimizing CNT distribution and system geometry for future engineering use, particularly in aerospace and energy systems

Purpose – In this study, the vibration analysis of composite plate reinforced with various volume fractions of multi-walled carbon nanotube (MWCNT) nanocomposite has been investigated analytically. Design/methodology/approach – The mathematical model for the vibration analysis of the plate was solved to evaluate the plate’s response and natural frequency for different design parameters. The first-order shear deformation theory was employed to formulate the governing differential equation of motion of the plate with simply supported boundary conditions. Findings – The plate structure used for the free vibration test comprises multi-layers of Perlon, Carbon, Kevlar and Kenaf, each with dimensions of 0.5 × 0.5 × 0.01 m. The matrix material used is the thermoplastic resin (orthocryl resin); it is widely used in biomaterial and energy applications to hold reinforcing materials such as Kevlar fibers, carbon fibers, or fillers. The material has several properties essential to composite structures, including flexibility, durability, strength and reinforcements. This composite fiber is oriented in two directions (Bidirectional at a 90� angle to each other). This results in a more balanced distribution of strength and stiffness in both directions. Nanoparticles with volume fractions of 0.5%, 1%, 1.5%, 2% and 2.5% were added. The results show that the free vibration characteristics and mechanical properties, including elastic modulus, response and natural frequency increase with the addition of volume fraction of the nanomaterial. Practical implications – The research could lead to the development of lighter, more efficient aircraft structures with enhanced vibration resistance and mechanical strength, contributing to better performance, fuel efficiency and safety. The developed reinforced composite could be utilized in aircraft elements where weight reduction and greater durability are crucial. Originality/value – The reinforcement of 2.5% MWCNT volume fraction increases the natural frequency of the composite plate by about 13.5% and the modulus of elasticity by 25.3%.

This study addresses free vibration analysis of rotating Functionally Graded Material (FGM) beams lying on elastic foundations using the Homotopy Perturbation Method (HPM). The HPM, a semi-analytical technique combining Homotopy from topology with perturbation methods to solve complex nonlinear equations, is employed to solve the resulting nonlinear eigenvalue problem. Its key advantages include effectively handling system inhomogeneity and nonlinearity while yielding insightful semianalytical expressions. The resulting governing equations, based on Euler-Bernoulli beam theory and Hamilton’s principle, are nondimensionalized to capture centrifugal stiffening, foundation interaction, and material gradation. The HPMis used to solve the obtained nonlinear eigenvalue problem, and the dimensionless natural frequencies and mode shapes are obtained for clamped-clamped (C-C), clamped-simply supported (CS), and clamped-free (C-F) boundary conditions. Validation against Finite Element Method (FEM) and Lagrange-based solutions confirms the high accuracy of HPM, with relative errors consistently less than 2%. Parametric studies show that dimensionless natural frequencies increase as η and λ increase, whereas the increase of the gradient index of FGM (n) leads to lower frequency values due to the severity degradation (ceramic to metal control). Importantly, C-C boundaries display a 4–5 times higher frequency than C-F configurations, emphasizing boundaries as key limiting factors for design. This study fills a significant void in rotating FGM beam dynamics and demonstrates HPM's capability for complex systems, providing valuable semianalytical tools for engineering design applications such as turbine blades, robotic arms, and rotating machines in extreme environments.

Specialist has attempted to treat or replace teeth in case of human dental damage as a result of illness or misuse at certain stages of life. Alternating force affects the life of teeth, and this force causes failure. In this study, partial molar denture was manufactured from a composite material, including polymethylmethacrylate acrylic with zirconia, at different weight fractions (0, 2.5, 5 and 7.5 wt%). Mechanical tests (compression and hardness) were conducted for these samples, and the best weight fraction was selected to manufacture the partial molar denture. The chewing force was measured using a F-sensor. Numerical solution was achieved using the solid work software to determine the best sample and study the distribution of the dental stresses. To predict the life of the denture experimentally, we designed and manufactured a new device that can determine the life of the dental by applying alternative load which simulates the force generated by chewing.

In this research, the thermal coating process was carried out using flame spraying technique using a gas mixture of oxygen and acetylene for the purpose of obtaining a surface layer of nickel-aluminum (metco450) coating on the surface of medium carbon steel type (AISI 1050) which provide an increase in surface properties and compensation of the base material when lost due to friction or wear. The research was carried out in three successive stages. The first stage included the preparation of the specimens and the design of the base surface of these specimens and Preparation of powder coating and analysis of chemical components for base material and powder coating. The second stage included the implementation of the coating process of (nickel-aluminum) powder by using the flame spray. The coating process was carried out in different ways for each model by changing the different spraying factors, which included the surface roughness of the specimens and the surface temperature of the specimens before the coating process. The third stage of the research included mechanical testing procedures of the coating layer. The tests showed that adhesion increases with increasing surface roughness of the sample prior to coating and the best adhesion is obtained when the base surface of the sample is heated to a temperature of (350 ºC) before the coating process. The resistance of the coating layer to wear is increased with the roughness of the base material surface of the sample due to the increased adhesion of the coating layer and the best resistance to wear when heating the surface of the base material of the sample before coating to temperature (350 ºC). The hardness of the coating layer is increased by increasing the roughness of the surface of the base material of the sample before the coating process and the best surface hardness of the coating layer when heating the surface of the base material of the sample before the coating process to (350 ºC).